1. Field of the Invention
The present invention relates to a substrate for organic EL which is used for forming organic layers, such as hole transportation layers and organic EL (electro-luminescence) layers, in predetermined pattern shapes, and to a method of manufacturing such a substrate.
2. Description of the Relates Art
A conventional organic EL element is manufactured in the following manner. First, a transparent ITO (indium tin oxide) film is deposited on a surface of a transparent substrate which may be a glass substrate. Next, the ITO film deposited on this substrate is patterned into first electrodes which are shaped like plural stripes, utilizing a photolithographic technique. The first electrodes correspond to anodes. Following this, electrical insulation banks (barrier walls) protruding beyond the substrate are formed surrounding the stripe-shaped first electrodes.
For patterning of organic layers such as hole transportation layers and organic EL layers on the substrate into desired pattern shapes, coating liquids containing materials for formation of the organic layers such as hole transportation layers and organic EL layers are applied upon the substrate as described below. According to the method of manufacturing an organic EL element described in Japanese Unexamined Patent Application Publication No. 2004-55159 for example, after pouring a hole transportation material onto first electrodes surrounded by banks and accordingly forming hole transportation layers, plasma treatment is performed upon tops of the banks with CF4 gas and the tops of the banks are fluorinated (liquid repellent treatment). Organic EL materials of red, green and blue are then put in this order each on each first electrode corresponding to each color through the hole transportation layers. Since the tops of the banks are liquid repellent, the organic EL material of each color is blocked from moving beyond the tops of the banks.
Next, by vacuum deposition, second stripe-shaped electrodes to be opposed against the first electrodes orthogonally are formed parallel to each other on the substrate, thereby sandwiching the organic EL materials between the first electrodes and the second electrodes. The second electrodes correspond to cathodes. In this manner, organic EL elements are fabricated in which the first electrodes and the second electrodes are arranged in a simple XY matrix and which are capable of displaying in full colors.
According to the conventional technique, the range of applying the hole transportation material is limited to between the banks and the plasma treatment is performed upon tops of the banks to make the tops liquid repellent, and therefore, it is possible to block the organic EL material of each color applied between the banks from moving over to other inter-bank areas and effectively prevent color mixing of the organic EL materials.